Conventional jet nebulizers require a significant amount of air for their operation, typically 15 liters per minute (L/min). With a typical I:E ratio of 1:3 and 15 breaths per minute (BPM), such a nebulizer would generate 1,000 milliliters (mL) of aerosol during a typical 4-second period of inspiration expiration. The tidal volume of a healthy adult may be on the order of 700 mL and that of a pediatric patient will generally be far less. Consequently, the large air flows provided by conventional jet nebulizers, when introduced into a ventilator circuit, may cause the sensing mechanisms of the ventilator circuit to produce alarms and potentially shut down its operation.
Nebulizer systems, such as micro pump systems, do not require a supply of air flow for their operation. Thus, they may be used in neonatal and adult ventilator circuits without fear of conflicting with the ventilator circuit sensors. Although micro pump nebulizer systems address the potential air flow problems that may occur when used with ventilator circuits, the attachments for a micro pump nebulizer system that would be used with the ventilator circuit are generally heavy, especially for pediatric application. Furthermore, the micro pump nebulizer systems are generally required to be kept upright during use.
Another way in which nebulizing devices have been implemented to avoid conflicting with the sensing mechanisms of a ventilator is to utilize nebulizing systems for delivering target aerosol directly into the lungs such as a nebulizing catheter synchronized with a patient's breathing to aid in the delivery of expensive or potential toxic drugs, and also to reduce environment contamination with certain drugs. These types of nebulizing systems are typically driven by a control unit to make sure the pressures of producing the aerosol do not conflict with the ventilator circuit activity. Specifically, some nebulizing systems would use a separate control unit that synchronizes with the ventilation pressure and only produce aerosol during the initial stages of inhalation, for example the first 70 percent of inhalation. These nebulizing systems are generally designed for higher pressure gas supply operation, for example 100 pounds per square inch (p.s.i.) thereby requiring a separate compressor or gas cylinder in addition to the control unit that manages when the pressurized gas is applied to generated aerosol.
Accordingly, there is a need for an improved aerosol delivery system for use with ventilators that makes up for the above-noted issues.